Birch: Aphids

• Categories: Birch Birch Insects Ornamental trees Ornamentals
• Last review date: 2026-02-27 11:28

Biology

Aphids are small yellowish to greenish insects often found on the underside of leaves and on new growth. Aphids on birch typically feed on the leaf veins and produce large amounts of honeydew, a sticky material which may attract ants or become covered with a black growth of sooty mold.

Developing leaves which have been injured by aphid feeding may show a typical “corrugated” or wrinkled growth pattern, with the insects often found on the underside in the distortions.

Some yellowing of the leaves may be observed with heavy aphid infestations.

Management Options

See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.

Non-chemical Management

Select non-chemical management options as your first choice!

• Hand-wipe or prune to control small, isolated infestations when practical.
• Wash aphids from foliage with a strong stream of water.
• Encourage natural enemies, including ladybird beetles, lacewings, and parasitic wasps.
• Control honeydew-feeding ants, which may protect aphid colonies.
• Provide proper nutrition. High levels of nitrogen in the foliage encourages aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.

Chemical Management

• Thorough coverage of foliage is important, including lower leaf surfaces.
• Apply when aphids are first noticed.
• Homeowners should not make foliar applications to trees over 10 ft tall.
• Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.

• All Seasons Horticultural and Dormant Spray Oil Concentrate [Organic]
  Active ingredient: mineral oil
  EPA registration number: 4-80
• Bug Buster-O [Organic]
  Active ingredient: pyrethrins
  EPA registration number: 1021-1771-54705
• R-T-U Year-Round Spray Oil
  Active ingredient: mineral oil
  EPA registration number: 6218-78
• Safer Brand BioNEEM Multi-Purpose Insecticide and Repellent Concentrate [Organic]
  Active ingredient: azadirachtin
  EPA registration number: 70051-6-42697
• Safer Brand Insect Killing Soap Concentrate II [Organic]
  Active ingredient: potassium salts of fatty acid
  EPA registration number: 42697-60
• This list may not include all products registered for this use.